A cellular communication system generally comprises a plurality of remote units in radio communication with a plurality of base sites, coupled to a centralized base station controller (CBSC). In some cases the base sites are coupled directly to a mobile switching center (MSC). The coupling means is generally via b-idirectional microwave or wireline terrestrial-based circuits such as T1 ISDN links. One communication system employing such a system layout is a Code Division Multiple Access (CDMA) communication system. A communication system utilizing the CDMA system protocol is described in detail in TIA/EIA Interim Standard IS-95A, Mobile Station-Base Station Compatibility Standards for Dual-Mode Wideband Spread Spectrum Cellular Systems, Telecommunications Industry Association, Washington, D.C. July 1993 (IS-95A) which is incorporated by reference herein.
In a CDMA communication system a packet scheme may be utilized to transport voice or data frames between a base station and a CBSC/MSC. As described in U.S. Pat. No. 5,363,404 APPARATUS AND METHOD FOR CONVEYING INFORMATION IN A COMMUNICATION NETWORK, such a packet scheme allows for the time offset (frame offset) of voice frames transmitted between the base station and the CBSC/MSC in consideration of frame offsets used for the packets as they are received/transmitted over the air interface. In such a communication system, each call can be assigned to one of 16 call groups or frame offsets, where a typical 20 ms (millisecond) air interface frame of information of a call in group number n (where n=0, 1, 2, . . . , 15) is sent/received by a base station with a time offset of 1.25*n ms. In other words, the frames of calls within one call group are "offset" in time by multiples of 1.25 ms from those in other call groups. Because a T1 span line operates at 1.536 Mbps, it can support 192 voice calls utilizing an 8 kbps vocoder, with a maximum of 12 calls in each of the 16 call groups. In other words, the maximum differential delay created by partitioning the T1 into 16 groups is 1.25 ms.
Utilizing such a frame offset technique for transmission between a base station and CBSC/MSC and such T1 partitioning requires an even distribution of calls among call groups for maximum traffic carrying capacity. An even distribution of calls among call groups is easy to achieve if there were no need for communication between more than one base station (i.e., no need for handoff or soft handoff). The need for soft handoff requires the same call group be utilized for communication between each base station in communication with the remote unit. In other words, a remote unit utilizing call group 1, must be kept in group 1 after handoff. Thus, a remote unit entering a cell may be blocked from handing off to that cell if the corresponding call group is filled (i.e., the call group has the maximum of 12 calls within the group), even if there exists space for the call in another call group. The inability to enter handoff leads to inefficient utilization of the communication system. Thus a need exists for a method and apparatus for optimizing information transmitted in a communication network that reduces the inefficient utilization of the communication system.